Creating a seal around a person's stoma, such that the seal is dependable, comfortable and conducive to body tissue, is important for the function of ostomy appliances. Once this seal has been made, the ostomy appliance may use one or more of a variety of techniques for managing stomal discharge. The term “ostomy” includes colostomy, ileostomy and urostomy. The formation of such a seal remains an area of continuous improvement and development, since the performance and comfort of the seal is fundamental to customer acceptance. One issue is protection of the external peristomal tissue where the normal skin and stoma tissue meet. Peristomal tissue can be extremely sensitive. Irritation can result if the peristomal tissue is exposed to body waste, or to repeated application and removal of adhesive or other sealants.
Some known devices use a single expandable balloon or member inside the stoma to form a seal against the inside wall of the opening, and a fixed stop or surface against the outside of the body. However, such devices have to be designed carefully to avoid the risk of damage to the sensitive internal tissue. In such designs, a relatively high concentration of force may result on the tissue underneath the stoma, especially when the external surface or stop is of limited conformability.
By way of example, U.S. Patent Publication No. 2003/0220621 describes a valved ostomy device including a hollow discharge tube and anchoring means for anchoring the tube in the stoma. The anchoring means comprises an inflatable balloon cuff inserted in the stoma to anchor the tube against the stomal wall, and a screw threaded clamp as an outer stop surface. Although the screw threaded clamp has a conformable pad, the anchoring means bears the entire weight of the ostomy appliance and any collection device attached to it. Thus, the strength of the attachment has to be offset against limitations on the clamping force which can be applied through the peristomal tissue without causing discomfort and tissue damage, and the inflation pressure of the balloon cuff without causing internal tissue damage to the stoma lumen.
EP0168967, EP1346711 and U.S. Pat. No. 4,950,223 describe ostomy ports comprising a single inflatable balloon inserted into the stoma, and an external adhesive wafer for securing the appliance to the skin around the stoma. Such designs are concerned primarily with the formation of a seal inside the stoma lumen. The peristomal tissue is either unprotected or is protected by the adhesive wafer, leaving the possibility that the peristomal tissue may be vulnerable to the conventional problem of irritation and pain resulting from exposure to stool or repeated applications and removals of adhesive.
Inflatable seals are also known from the field of rectal appliances. However, such designs are not generally applicable to ostomy appliances, because the anus is very different physically from a stoma. Nature has engineered the anus to be naturally robust to withstand exposure of tissue to stool, and the pressures associated with containing stool. In contrast, a stoma is an artificial opening formed by surgery, and is much more delicate. Moreover, ostomy appliances often have to carry the long-term weight of a collection pouch, whereas rectal devices normally do not have to support such long-term weight.